Board Feet Calculator – One Board Size, Tallied in Bulk
A board foot is the lumber trade’s unit of volume — 144 cubic inches of wood. Enter one board size and how many of them you have, and this page tallies that size: board feet per board, total board feet, and total cost.
Building a mixed-size project list instead? Board Foot Calculator starts with one board size and adds a row for each different size, keeping the whole project’s total board feet and cost.
The boards
🔒 Everything is calculated in your browser — nothing you enter leaves your device.
The tally
The board, piece by piece
The name is not the size
You typed full measurements — 2 in × 6 in — so this count uses exactly those. Boards sold by a nominal name measure less than the name says: pick one above and watch the count drop.
One board foot, drawn to scale
The plank below is your board — its labels follow the numbers you enter. A board foot is the slab in outline beside it: 12 inches long, 12 inches wide, 1 inch thick. Every board is just a stack of those slabs, counted by volume.
The arithmetic behind the picture: thickness × width × length gives cubic inches, and 144 cubic inches make one board foot. Divide by 144 with the length in inches — or by 12 with the length in feet, which is the same division wearing a coat.
The one idea underneath all of it
A board foot is a volume, not a length and not an area. A short, wide, thick board can hold more board feet than a long skinny one, and two boards with the same name can hold different amounts of wood once one of them is measured honestly. Count the volume and the name stops mattering.
Nominal names, actual boards
The finished sizes below are the US dressed-lumber standards (the American Lumber Standard, NIST PS 20), and the last column is what each board really holds at the common 8 ft length — counted by the tape measure, not by the name.
| Nominal name | Actual size (in) | Board feet at 8 ft |
|---|---|---|
| 1 × 4 | 0.75 × 3.5 | 1.75 bf |
| 1 × 6 | 0.75 × 5.5 | 2.75 bf |
| 1 × 8 | 0.75 × 7.25 | 3.63 bf |
| 1 × 12 | 0.75 × 11.25 | 5.63 bf |
| 2 × 4 | 1.5 × 3.5 | 3.50 bf |
| 2 × 6 | 1.5 × 5.5 | 5.50 bf |
| 2 × 8 | 1.5 × 7.25 | 7.25 bf |
| 2 × 10 | 1.5 × 9.25 | 9.25 bf |
| 2 × 12 | 1.5 × 11.25 | 11.25 bf |
| 4 × 4 | 3.5 × 3.5 | 8.17 bf |
| 4 × 6 | 3.5 × 5.5 | 12.83 bf |
Lengths, unlike cross-sections, are honest: an 8 ft board is 8 feet long. Only the thickness and width shrink between the sawmill and the shelf.
Pairs well with this calculation
Volumes, areas and the jobs a lumber tally feeds into.
A board foot is the lumber trade’s unit of volume — 144 cubic inches of wood — and it is what the price tag at a hardwood yard is really counting. Enter the thickness, width and length of your boards, pick a nominal size like 2×6 and let the page convert it to the dimensions the board actually measures, and see both the board feet in your pile and what it should cost before you get to the yard.
Key takeaways
- A board foot is the slab in outline beside it: 12 inches long, 12 inches wide, 1 inch thick.
- board feet = thickness (in) × width (in) × length (ft) ÷ 12
- The name on the rack is the rough size the board started as, not the size it is now.
Contents
Board feet in three steps
Measure the real board
Put the tape across the thickness and width — or pick the board’s nominal name above and let the page fill in the finished size. The name on the rack is the rough size the board started as, not the size it is now.
Multiply, then divide
Thickness × width × length, divided by 12 when the length is in feet (by 144 when it is in inches). The answer is the volume of the board in board feet — every board foot is 144 cubic inches of wood.
Count the pile, price the pile
Multiply by the number of boards for the total, then by the yard’s price per board foot for the cost. Now you know what the pile should cost before anyone writes it on a tally sheet.
How the board feet calculator works
board feet = thickness (in) × width (in) × length (ft) ÷ 12
The example on this page. A full-size board measuring a true 2 in × 6 in, 8 ft long — the kind a small mill sells rough-sawn. 2 × 6 × 8 = 96, and 96 ÷ 12 = 8.00 board feet. At $5.50 per board foot, that one board costs $44.00.
The nominal trap. Now buy a “2×6” at a lumber yard. The board in your hand measures 1.5 in × 5.5 in, so its true count is 1.5 × 5.5 × 8 = 66, and 66 ÷ 12 = 5.50 board feet — not 8.00. Order twenty for a deck and the pile holds 110 board feet, not 160; at $5.50 the honest tally is $605.00, not the $880.00 the names alone would suggest.
The same board, measured in inches. An 8 ft board is 96 in long, and with the length in inches the divisor becomes 144: 1.5 × 5.5 × 96 = 792 cubic inches, and 792 ÷ 144 = 5.50 board feet. Identical answer — the two forms of the formula are the same arithmetic.
A wide board. A full-size 1 × 12, 6 ft long: 1 × 12 × 6 = 72, and 72 ÷ 12 = 6.00 board feet. Ten of them make 60.00 board feet — flat, wide boards add up faster than their modest thickness suggests.
How the numbers are rounded. Board feet are carried unrounded through the quantity and price steps, and only the displayed answers are rounded: board feet to two decimal places, money to the cent. That is why a per-board figure and a total can differ by a cent from what you would get by multiplying the rounded numbers on screen — the screen is rounded, the arithmetic is not.
Going deeper
The name is a fossil. A 2×4 starts life at the sawmill as a rough board genuinely close to 2 in × 4 in — green, wet and hairy with saw marks. Then two things happen to it. It is dried, and wood shrinks as it dries. And it is planed smooth on all four faces, which shaves off more wood still. What reaches the shelf is a finished board of 1.5 in × 3.5 in, but the trade never stopped calling it by the size it was cut to.
The finished sizes are not whatever a mill feels like: they are fixed by the American Lumber Standard (NIST PS 20), the same table reproduced above, so a 2×6 is 1.5 × 5.5 in every yard in the country. Two honest exceptions exist. Rough-sawn lumber from small local mills is often sold at full dimension — a true 2 in × 6 in — which is why this page lets you type measurements as well as pick names. And lengths never shrank: the standard only dresses the cross-section, so an 8 ft board really is eight feet long.
Building centres usually price dimensional softwood by the piece — the 2×6 has a sticker price and that is that. Hardwood yards work differently: oak, walnut, cherry and their exotic cousins are priced per board foot, because the boards arrive in random widths and lengths and volume is the only fair measure. You pick your boards, the yard tallies the board feet — often with a marked tally stick or a board-foot ruler — and the price per board foot for that species and grade does the rest. The count on this page is the same count the yard will make.
Two habits of that world are worth knowing. Hardwood thickness is named in quarters: 4/4 (said “four-quarter”) is one inch thick in the rough, and surfaced two sides it finishes near 13/16 in — use the finished figure when the board has already been planed. And nobody buys the exact tally: between saw kerfs, checks, knots and the board that warps on the way home, experienced buyers add a waste allowance of roughly ten to fifteen percent on top of the project’s board feet. Count your project honestly, then order the pile a little fat.
What a board foot is, and what the log scales do
One board foot is 144 cubic inches — a board 1 foot long, 1 foot wide, and 1 inch thick. Everything else in lumber pricing is a conversion from that volume, and every log sale needs its scale named.
Board feet equal thickness in inches times width in inches times length in feet, divided by 12. A 2-by-6 board 8 feet long is 8 board feet; a 1-by-12 board 10 feet long is 10 board feet; a 4-by-4 board 6 feet long is also 8 board feet, because the volume is the same in a different shape. Board footage is calculated from nominal dimensions — the size lumber is sold as, not the smaller surfaced size — which is the convention of the trade and the reason a tape measure on a finished board will not match the yard ticket. To convert board feet to the surface a stack will cover, divide by the thickness in inches; to convert to linear feet, multiply board feet by 12 and divide by thickness times width; and 12 board feet make exactly 1 cubic foot.
Logs are estimated with a log scale, not the board formula, because a round tapered log must be converted to rectangular boards. The Doyle scale uses (diameter minus 4) squared times length divided by 16, with diameter in inches at the small end inside bark, and it underestimates small logs badly while converging on large ones. The Scribner scale counts the boards drawable inside the small-end circle and is more generous on small logs. The International scale allows for taper and a specified kerf and is generally regarded as the most accurate. The same log has a different board-foot content under each scale, so any log sale should name the scale, the diameter measurement point, the length, and the kerf where the International scale is used — without those four, two figures for the same log cannot be compared.
The companion guide works the definition three ways, the square-foot, linear-foot, and cubic-foot conversions with worked examples, the three log scales with a worked Doyle calculation, how to measure a board and a log, and how to check a yard ticket: total board footage, price per board foot, and total price, multiplied and compared.
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches — the volume of a board 12 inches long, 12 inches wide and 1 inch thick. It is the standard measure for pricing rough and hardwood lumber in the United States and Canada, because boards of random width and length can all be reduced to one fair count of how much wood is actually there.
How do I calculate board feet?
Multiply the thickness in inches by the width in inches by the length, then divide: by 12 if the length is in feet, or by 144 if the length is in inches. A board measuring 1.5 in × 5.5 in × 8 ft gives 1.5 × 5.5 × 8 = 66, and 66 ÷ 12 = 5.50 board feet. Multiply by the number of boards for a pile, and by the price per board foot for the cost.
Why is a 2×4 actually 1.5 × 3.5 inches?
Because the name records the size of the rough board at the sawmill, before it was dried and planed. Drying shrinks the wood and surfacing all four faces shaves it further, and the finished sizes are standardised nationally by the American Lumber Standard (NIST PS 20): a 2×4 finishes at 1.5 × 3.5 in, a 2×6 at 1.5 × 5.5 in, and so on. The length is not dressed down — an 8 ft board is a true 8 ft.
How many board feet are in a 2×4 that is 8 feet long?
Counted by its actual measurements, 3.50 board feet: 1.5 × 3.5 × 8 ÷ 12. Run the name itself through the formula instead and you get 2 × 4 × 8 ÷ 12 = 5.33 board feet — a number no real 2×4 contains. That gap, on every board in a project, is exactly why this calculator converts nominal names to actual sizes before it counts.
Should I use nominal or actual dimensions?
Actual, whenever the answer matters — ordering wood, checking a yard’s tally or pricing a pile. The volume of the board is the volume of the wood that exists, and only the finished measurements describe that. Nominal names are fine for talking about a project and for finding the board on the rack; they are the wrong numbers for arithmetic. The one exception is full-dimension rough-sawn lumber from small mills, which really does measure what it is called.
How much does a board foot of lumber cost?
It depends on the species, the grade and where you are buying. Common softwoods and workhorse hardwoods like red oak sit at the modest end, furniture walnut and cherry in the middle, and imported exotics far above them — and prices move with the lumber market. Yards post their price per board foot by species, so enter the figure from your own yard above and the calculator prices your pile with it; clear the price field if you only want the count.
Is a board foot the same as a square foot?
No. A square foot is an area, 1 foot by 1 foot. A board foot is a volume, that area 1 inch thick, or 144 cubic inches. Board feet equal square feet times thickness in inches, so the two coincide only for a board exactly 1 inch thick. To find the surface a stack of boards will cover, divide the board footage by the thickness in inches.
How many board feet are in a 2×4 that is 8 feet long?
5.33 board feet, using nominal dimensions: 2 times 4 times 8 divided by 12 is 5.33. A 2-by-4 contains two thirds of a board foot per foot of length, so a 10-foot 2-by-4 is 6.67 board feet and a 12-foot one is 8 board feet. Actual surfaced dimensions are smaller, but board footage is calculated from nominal dimensions as lumber is sold.
Which log scale should a log sale use?
Whichever scale the contract names — the essential point is that it is named. Doyle, Scribner, and International give different figures for the same log, with Doyle lowest on small logs and International generally the most accurate. A sale that states the scale, the small-end diameter inside bark, the length, and the kerf can be checked; a sale that states only a board-foot total cannot.
Related calculators
Volume, area and coverage — the rest of the project shelf.
Mixed sizes for one project? See the Board Foot Calculator — one board size first, then a row for each different size.
Cubic Feet Calculator
Any volume in cubic feet.
→Square Footage Calculator
Areas in square feet.
→Paint Calculator
Paint for the finished job.
→Area Calculator
Area of any flat shape.
→Concrete Calculator
Concrete volume for slabs and footings.
→What Is a Board Foot?
Definition, log scale, and square-foot conversions: 144 cubic inches, the formula, and Doyle, Scribner, and International scales.
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